VALUE OF CACTI AS FOOD FOR STOCK. 9 



Fortunatoly tliore was a ijreat difTerenco between the rainfall durino: 

 the months from January to March of 1904 and 1905. The eirect 

 upon the water content of the plants is fairly well illustrated in the dif- 

 ferent tables of analyses, although no special eilort was made to collect 

 the samples for the jmrpose of showinjj; this feature in detail. There 

 are some apparent exceptions to the rule that the samples collected 

 in 1904 contain more water than those collected in 1905; but this 

 may be accounted for in some cases by the difference in the portions 

 of plant collected or in other cases possibly by local conditions. 

 The amount of water in the difl'erent samples analyzed varied from 

 60.99 to 95.5 per cent. The miscellaneous o;roup is relatively more 

 succulent than cither of the other two, the average amount of water 

 being 87. S8 i)er cent, while the prickly pears averaged 84.26 per cent 

 and the cane cacti 78.47 per cent. As a nde, the fruit contained 

 more water than the stems and the younger growth more than the 

 older. 



The (liiTcrcnce in the species in the field during a dr\' and a wet 

 season is very marked, and even prickly pear has its limit of drought 

 endurance. Experience in southern Texas demonstrates that it is 

 much reduced in value during very prolonged dry seasons, for it 

 becomes tough and leathery. "Fat pear" is largely the result of 

 distention of the tissues by water. wSome species, Opuntia fulgida 

 especially, when a favorable moist season follows an exceptionally 

 dry one, wnll absorb so much water that the fruits and yoimg joints 

 become ruptured by the excessive turgidity, and this often occurs 

 with the fruit of nopal canmeso and other cultivated Mexican species. 



ASH CONTENT. 



Plants grown in the arid and semiarid Southwest, where there is an 

 abundance of soluble salts in the soil, are found to contain more ash 

 than those grown in regions of frequent rainfall. The cacti are cer- 

 tainly no exceptions to this rule. The average ash in the air-dried 

 stems and fruits of the prickly pears anal3'zed amounts to 18.25 per 

 cent, for the cane cacti 15.50 per cent, and for the miscellaneous group 

 13.54 per cent, one sample running as high in ash as 33.8 per cent of 

 the air-dried substance. These averages would be still liigher if they 

 did not include the ash of fruits, which always contain less ash than 

 the stems. The average ash in the air-dried fruits of the prickly 

 pears, for instance, is 13.21 per cent, which is 5.4 per cent less than is 

 contained in an average of both stems and fruits of this group and 6.35 

 per cent less than is in tlie stems alone. It is the seed which is espe- 

 cially low in ash, the fleshy portion resembling the stem more closely 

 so far as its ash content is concerned. This is brought out very 

 forcibly in samples Nos. 8022a and 80226, the former being the fleshy 



103—1 



